Subject: GCS Mount v1.69.2: "Cannot insert legacy ACL" with Uniform Bucket-Level Access - Uploads Fail
What is the problem you are having with rclone?
Files copied to a GCS mount (with --vfs-cache-mode full) are not uploading to the actual GCS bucket. The files appear in the local mount (served from VFS cache) but never make it to the cloud.
The rclone logs show repeated errors during VFS upload attempts: googleapi: Error 400: Cannot insert legacy ACL for an object when uniform bucket-level access is enabled.
This occurs even when the rclone.conf has no object_acl / bucket_acl lines, or when they are explicitly set to blank (e.g., object_acl =).
Read operations from the mount work fine (files added via GCS console are visible). Rclone version is v1.69.2 on Windows.
Run the command 'rclone version' and share the full output of the command.
rclone v1.69.2
- os/version: Microsoft Windows 10 Pro 22H2 22H2 (64 bit)
- os/kernel: 10.0.19045.5737 (x86_64)
- os/type: windows
- os/arch: amd64
- go/version: go1.24.2
- go/linking: static
- go/tags: cmount
Which cloud storage system are you using?
Google Cloud Storage (GCS). The bucket is configured with Uniform Bucket-Level Access enabled.
The command you were trying to run
rclone mount gcs:artemis-cloud-storage G: --vfs-cache-mode full --skip-links -vv --log-file C:\rclone\rclone-mount.log
Please run 'rclone config redacted' and share the full output.
[gcs]
type = google cloud storage
project_number = XXX
token = XXX
(I have tried as-is, plus manually adding object_acl = and bucket_acl = lines, the error persists).
A log from the command that you were trying to run with the -vv flag
Key error messages from the log (rclone version v1.69.2):
2025/05/06 14:26:05 ERROR : 3.jpg: Failed to copy: googleapi: Error 400: Cannot insert legacy ACL for an object when uniform bucket-level access is enabled. Read more at https://cloud.google.com/storage/docs/uniform-bucket-level-access, invalid
2025/05/06 14:26:05 ERROR : 3.jpg: vfs cache: failed to upload try #1, will retry in 10s: vfs cache: failed to transfer file from cache to remote: googleapi: Error 400: Cannot insert legacy ACL for an object when uniform bucket-level access is enabled. Read more at https://cloud.google.com/storage/docs/uniform-bucket-level-access, invalid
This error pattern repeats for every file attempted to be uploaded by the VFS cache. The mount eventually stops.
(I can provide the full log file if needed.)